The present invention relates to electrical cables, and, in particular, to the shielding of electrical cables at the termination thereof, and, more particularly, to shielding of electrical cables from electromagnetic interference and electromagnetic pulses (EMI/EMP) from entering therein.
One method of shielding is that used in coaxial cables having one main conductor therein separated from the outer tube wall by dielectric material The outer tube wall is covered by a metal braid being tube shaped and has a further protective coating of rubber thereabout, for example. The metal braid is exposed and the cable itself is placed through a clamp nut. The braid is pulled back against the clamp nut and then a metal ferrule is placed on the dielectric core clamping the metal braid to the clamp nut. A connector body is then placed over the ferrule and threaded onto the clamp nut thereby totally securing the coaxial cable end. The device is clearly appropriate for coaxial cables having a single conductor therein but would be difficult to apply if multiple conductors are therein. See U.S. Pat. No. 3,110,756, for example.
Another prior method of shielding of a cable having multiple conductors therein with a metal braid thereabout uses magnetic pulse forming apparatus to securely clamp the cable to an appropriate fitting. The metal braid at the cut end is placed about a ring which is inserted into a shell having appropriate sized ends. The magnetic pulse forming apparatus compresses the shell and ring about the cable to make a secure fitting. See U.S. Pat. No. 3,992,773 which is incorporated by reference.
U.S. Pat. No. 3,280,246 discloses a cable having a multitude of conductors with metal braid about each. The braid of each conductor is removed to a short distance of the cut ends and is secured in between the metal rings uniformly about the rings. The above patent is incorporated by reference.
A method of grounding the metal braid of the cable is shown in U.S. Patent which is also incorporated by reference.
As seen from the above, there is a need to be able to connect each metal braid to the backshell to provide proper EMP shielding.